function Person(firstName, lastName) {
    this.firstName = firstName;
    this.lastName = lastName;
  }
  Person.getFullName = function() {
    return `${this.firstName} ${this.lastName}`;
  };
  // 因为member只能继承来自实例化对象的原型链原来有的属性和方法
  const member = new Person("Lydia", "Hallie");
 // new的过程会返回一个对象，this会指向
  
//   console.log(member.getFullName());

  console.log(Person.getFullName());
